Rates of women who are opting for preventive mastectomies, such as Angeline Jolie, have increased by an estimated 50 percent in recent years, experts say. But many doctors are puzzled because the operation doesn't carry a 100 percent guarantee, it's major surgery -- and women have other options, from a once-a-day pill to careful monitoring.

Health officials fear the trend could undermine gains made in fighting the AIDS pandemic and provoke a surge in cases. Globally, about 33 million people are thought to have HIV and nearly 3 million people are newly infected every year.

"If the law is applied badly, this could set us back and do incredible damage," said Paul de Lay, an AIDS expert at UNAIDS, who was not involved in the report.

De Lay said the laws could result in forced testing and drive the epidemic underground as people hide their HIV status, allowing the virus to spread unnoticed.

According to Planned Parenthood, 58 countries worldwide have laws that criminalize HIV or use existing laws to prosecute people for transmitting the virus. Another 33 countries are considering similar legislation.

Since 2005, seven countries in West Africa have passed HIV laws. In Benin, simply exposing others to HIV is a crime, even if transmission doesn't occur. And in Tanzania, intentional transmission of the virus can lead to life imprisonment.

Many of the laws in Africa were passed after a meeting in Chad in 2004 sponsored by the U.S. Agency for International Development, the world's biggest funder of AIDS programs, and attended by U.N. officials.

"The U.N. was definitely remiss to allow this to happen," said Kevin Osborne, a senior HIV adviser at IPPF and one of the report's authors.

De Lay said UNAIDS found out about the meeting only after it happened.

But poor countries aren't the only ones using these laws.

In the U.S., 32 states have laws criminalizing HIV transmission. Experts estimate that thousands of people have been charged across the country with spreading HIV.

Since 2001, 16 people in the United Kingdom have been prosecuted for spreading HIV.

In 2005, a woman in Canada was charged with criminal negligence and aggravated assault for passing HIV while pregnant to her baby.

She did not tell her doctors that she had HIV and did not receive the medications necessary to prevent the virus from infecting her child. She was sentenced to a six-month conditional sentence followed by three years of probation.

In countries like Britain, Canada and the U.S., which are major donors of efforts to fight AIDS in Africa, such cases are particularly unfortunate, many experts say.

"It sets a poor example in the sense that other countries may then think this is an appropriate or desirable way to deal with HIV," said Richard Elliott, executive director of the Canadian HIV/AIDS Legal Network.

While there might be exceptional cases where prosecuting people who are maliciously spreading HIV makes sense, experts said those were extreme cases.

"The criminal law is a blunt instrument," Osborne said. "If you put everyone in prison with HIV, then you think you've controlled it. But you haven't dealt with the issues around the intimate behaviors that spread HIV."

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